Make a steam bath by boiling water and placing a bowl on the top. Combine the sugar, egg, butter, honey, and milk in the bowl. Whisk the mixture until the ingredients double in volume.
Stir in the cacao slowly, followed by the baking soda.
Remove the batter from the steam batch. In small parts, add the flour to the mixture. At first, use a whisk to stir the flour in. Once it begins to thicken, switch over to a spatula. As it cools, the batter will begin to thicken.
Divide the dough into 11 equal balls, they should come out to make 11 inch cake.
On a floured surface, roll out each dough portion into a thin, circular layer. Measure it using a plate to ensure they are consistent in size.
Bake at 350°F for about 5-8 minutes, depending on your oven. Remove the cake layer from the oven and place the plate you measured it with on top. Trim off the excess edges of the dough by tracing a knife alongside the edges of the plate. Remove it form the baking sheet and place it onto a cooling rack. Repeat until all the layers are baked and trimmed.
Spartak Cake Cream
Whisk the eggs with flour together until all the lumps are gone.
Pour the milk into a heavy saucepan and add in the egg mixture, vanilla, and sugar. Cook on medium-low heat, stirring/whisking consistently until the mixture resembles the consistency of sweetened condensed milk. Remove the cream from heat and let it cool completely at room temperature.
Using an electric mixer, whisk the room temperature butter until it's smooth in texture. In small parts, add in the cooked cream. Continue whisking until well-combined.
Assemble the Cake
Distribute around 80% of the cake cream across the cake layers. Spread it evenly and stack the layers on top of one another. Use the remaining cake cream to decorate the outside of the cake.
Decorate the outside of the cake as you wish or leave it as-is. Chill it in the fridge before serving and enjoy!